[Quest API] Add GetEXPForLevel() to Perl/Lua (#3403)

# Perl
- Add `$client->GetEXPForLevel(check_level)`.

# Lua
- Add `client:GetEXPForLevel(check_level)`.

# Notes
- This allows operators to see the required experience for a level based on the client provided, this takes race/class modifiers into account as well if enabled.

zone/lua_client.h

@@ -468,6 +468,7 @@ public:
 	void UseAugmentContainer(int container_slot);
 	bool IsAutoAttackEnabled();
 	bool IsAutoFireEnabled();
+	uint32 GetEXPForLevel(uint16 check_level);
 
 	void ApplySpell(int spell_id);
 	void ApplySpell(int spell_id, int duration);